Apparatus and method for data security in an optical disk storage system

ABSTRACT

An optical storage disk for use in an optical storage system includes a storage layer which is capable of being disrupted when a laser beam of sufficient intensity is focused thereon. The optical storage disk has a transparent substrate layer on one side of the storage layer and a lacquer layer on the other side of the storage layer. The disruptions provided by the laser beam are selected to provide human readable and/or machine readable patterns. To reduce the damage to portions of the optical disk other than the storage layer, the storage layer is exposed to the laser beam prior to curing, or prior to applying and curing the lacquer layer. The optical disk can be of the type with data written thereon during fabrication, or the disk can be of the type in which data can be impressed thereon after fabrication of the optical disk. The patterns on the optical disk can be in the form of optical bar codes. In one application of the present invention involving the type of disk on which data can be written after fabrication, the pattern resulting from application of the laser beam to the disk is read by an optical reading device and transferred to the disk in the data format. The resulting embedded characters are used, in conjunction with files stored on the medium, to provide security against unpermitted access to the files. In addition for writable optical storage medium, the embedded characters can be used to prevent inappropriate material from being stored on the optical storage medium

This is a divisional of application Ser. No. 07/999,626 filed on Dec.31, 1992, now U.S. Pat. No. 5,489,768, which is a continuation-in-partof copending application Ser. No. 07/810,976 filed on Dec. 20, 1991, nowU.S. Pat. No. 5,430,281.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates generally to optical information storage andretrieval systems and, more particularly, to techniques for providingsecurity for the data stored in the optical information storage andretrieval system. The increased system security is provided by theinclusion in the medium of a visible and indelible identifying code andthe storage of related data files on the storage medium. The visibleidentifying code is used in conjunction with the related files by theapparatus accessing the data files to protect the data files stored onthe media against unauthorized access to the data files and/orunauthorized copying of the data files.

2. Description of the Related Art

Optical storage medium, and particularly, the optical disk is currentlyfinding increasing use in the high density storage of large quantitiesof data. In the optical medium, the information is retrieved through theinteraction of a radiation beam with the information storage medium. Atpresent, three principal types of optical storage media are in commonuse. The first type of optical storage medium is manufactured with theinformation stored thereon, generally in the form depressions formedinto a polycarbonate substrate. A reflecting coating is deposited on thepolycarbonate substrate and the radiation beam is focused on thereflecting layer. This type of optical disk is frequently referred to,in the disk embodiment, as a CD audio disk or a ROM (i.e., read onlymemory) disk. The second type of optical storage medium has thecapability of having information recorded (written) thereon at some timeafter the fabrication of the medium. Such an optical storage medium inthe disk embodiment is frequently referred to as a writable opticalstorage disk. The third type of optical storage medium has the capacityto have information recorded on the medium after fabrication. Inaddition, at a later time, the stored information can be erased ormodified. This type of optical storage medium in the disk embodiment isgenerally referred to as an erasable or a re-writable optical storagedisk. In each type of optical storage (disk) medium, the storage layeris supported and protected by a polycarbonate support substrate and by aprotective (lacquer) overcoat layer. However, the storage layer ismodified in the writable disk and in the erasable disk. The storagelayer in the writable disk includes a reflector layer (generallyfabricated from gold) proximate the lacquer overcoat layer and includesa recording layer, typically a dye polymer layer, proximate thepolycarbonate layer. The newly fabricated writable optical storage diskhas a recording layer that is responsive to radiation having selectedparameters, the radiation changing the optical properties of therecording layer. ,Differences in the optical properties of the recordinglayer can be detected, through the interaction with an impingingradiation beam and data, encoded by means of the optical propertychanges, can be recovered. In order to simplify the discussion, therecording, storage, and/or the reflective layer of the writable opticaldisk will be referred to as the storage layer. In the opticalinformation storage and retrieval system, a read/write head is moved ina specified path relative to the optical storage medium. The read/writehead provides a radiation beam which, after interacting with a region ofthe optical storage medium, is detected. The information stored on theoptical storage medium takes the form of data-bearing regions withdiffering optical properties depending, for example on the logical statebeing represented by the particular region. The radiation beam which hasinteracted with the optical storage medium has detectable differencesresulting from the interaction with the data-bearing regions. Thesedetectable differences are converted into electrical signals. Theelectrical signals are subsequently converted to a format which can beconveniently manipulated by a signal processing system.

In order to provide security for the data stored on optical storagemedium, a need has been felt for a technique for providing permanent anddifficult-to-compromise identification marking for the optical storagemedium. Using this identification marking, the data stored on the mediumcould be determined by and/or related to the marking. In addition, anyproblems that might originate with the manufacturing process can berelated to disks fabricated during the same period of time or even tothe same batch. The history of the usage of the disk can be determinedwhen a record is kept of the identifying information at the time of theaccessing of the disk.

In the prior art, identification markings have been applied to thesurface of the disk by means of mechanical disruption of the surface orby deposition of legible material on the surface. This information,however, being on the surface of the disk can be compromised eitheraccidentally or intentionally.

Recently, in U.S. Pat. No. 4,961,077 issued in the name of D. L. Wilsonet al., a technique for the permanent labelling of the disks wasdescribed. Specifically, the metal reflective layer, upon which thepermanent identification information is stored as areas of varyingreflectivity, is marked by means of a pulsed laser. The pulsed lasercauses an indelible marking on the reflective layer, a marking which isprotected by the same transparent coating which protects the reflectivecoating. The process described in the Wilson reference is extremelysensitive to the energy level of the laser beam, too small an energylevel in the laser beam not providing an identifiable marking, while toomuch energy can disrupt the lacquer overcoat layer and/or thepolycarbonate layer used to protect the reflective layer. The disruptionof the storage layer can result in damage to the surrounding portions ofthe optical disk. In addition, applying the laser beam to the reflectivesurface through the narrower of the two protective coatings isrecommended to minimize the destructive effects of the laser beamresulting from the passage of high intensity radiation through thelayers.

Therefore, in order to provide a mechanism for providing security fordata already written on a storage medium or for data to be written ofthe storage medium, a need has been felt for a technique for providingindelible identifying markings for the optical storage media which isrelatively insensitive to the power of the radiation beam and whichreduces the damage to the optical disk. Also needed is a technique forenhancing the machine readability of the disk markings. Furthermore, aneed has been felt for apparatus and a method to incorporate theindelible markings in a system in which the disk can be used to insurethe unauthorized access to the information stored on the disk.

SUMMARY OF THE INVENTION

The present invention is directed to overcoming one or more of theproblems set forth above. Briefly summarized, according to one aspect ofthe present invention, the identification marking is applied to thestorage layer of the optical disk prior to the curing of the protectivelacquer overcoat or prior to the application of the protective overcoatitself. Because the lacquer overcoat, prior to curing of this material,is relatively elastic, the disruption of the overcoat as a result of thelaser interaction with the reflective layer can be accomplished withoutexcessive damage. The markings provided by the laser beam are arrangedin preselected patterns, the patterns including machine readable andhuman readable information. In the alternative, the marking by the laserbeam can be applied before the overcoat is actually applied. Accordingto one embodiment, optical bar code patterns can be printed in a mannerthat the position of an optical bar code reader relative to the centerof the disk is irrelevant in interpreting the optical bar code message.With the indelible markings are placed on the storage medium, the datafiles stored on the on the optical storage disk can include encodedsignal groups which, when decoded, can be automatically compared withthe visible markings. The stored signal groups, when consistent with thevisible medium markings, can be additionally used to provide a decodingkey for the data files stored on the disk. The system accessing thestorage medium can be provided with a system identification code whichcan be (automatically) compared to the medium identification to insurethat an unauthorized system is not attempting to interact with thestorage medium. The identification and markings prevent inappropriatefiles from being stored on the medium.

The identification markings and the files of the present invention canbe advantageously used to prevent unauthorized access the files on theoptical medium. The system attempting to access the data files mustfirst determine that the identification markings are consistent withencoded signal groups stored on the disk. When the identificationmarkings and the encoded signal groups are consistent, then access tothe data files on the storage medium is permitted. However, the datafiles may contain a decoding key which must be used by the accessingsystem to read the stored data files. For data files to be stored on theoptical storage medium, preselected data signal groups can be requiredto permit the storage. The preselected data signal groups are comparedwith the identification markings and/or the medium identification signalgroups to insure that only appropriate data files are stored on thestorage medium.

These and other aspects, objects, features and advantages of the presentinvention will be more clearly understood and appreciated from a reviewof the following detailed description of the preferred embodiments andappended claims, and be reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of an optical storage disk of the typegenerally referred to as a read-only optical storage disk.

FIG. 2 is a cross sectional view of an optical disk of the typegenerally referred to as a writable optical storage disk.

FIG. 3A illustrates a first embodiment of a process by which machinereadable and human readable information can be indelibly fixed in theoptical storage media, and FIG. 3B illustrates a second embodiment of aprocess by which machine readable and human readable information can beindelibly fixed in an optical storage media.

FIG. 4A is a cross sectional view of a mark in an optical storage diskgenerated as a result of the process illustrated in FIG. 3A, while FIG.4B is a cross sectional view of a mark in an optical storage diskgenerated as a result of the process illustrated in FIG. 4B.

FIG. 5 illustrates an optical disk having machine readable and humanreadable text printed thereon.

FIG. 6 illustrates how the optical bar code characters are formedaccording to the present invention.

FIG. 7 is a block diagram of the storage medium and the read/write headincluding apparatus associated therewith of the storage and retrievalunit.

FIG. 8 is a representational view of the file structure stored on thestorage medium according to the present invention.

FIGS. 9, 9A and FIG. 9B depict a flow diagram illustrating theinteraction of the storage medium interaction system according to thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

1. Detailed Description of the Figures

Referring to FIG. 1, a cross-sectional view of a read-only opticalstorage disk 10 for storing prerecorded data (in a form which can beidentified by a radiation beam interacting with the disk) is shown.Transparent polycarbonate or substrate layer 12, or similar material hasan optical transmission characteristic which permits the radiationinteracting with the storage layer structure of the optical disk to betransmitted therethrough. The polycarbonate layer also acts as a supportand protection layer for the remainder of the optical disk. Next to thepolycarbonate layer 12 is the aluminum reflector layer 11. Thepolycarbonate layer 12 is fabricated with the stored information as asurface structure. The reflecting layer is deposited in such a manner asto provide a surface generally retaining the structure of thepolycarbonate surface. A lacquer or other protective overcoat layer 13is applied to the aluminum reflector layer in an uncured state. Thelacquer or protective layer is typically of the type which is cured byultraviolet radiation and the cured lacquer layer 13 supports andprotects the aluminum reflector layer 11. In the past, identificationmarkings 14 have been typically printed on the surface of the lacquerovercoat layer 13 or mechanically scribed in the surface of lacquerovercoat layer 13.

Referring to FIG. 2, a writable optical storage disk 20 used for thestorage of information is shown. In this type of optical storage disk,the data can be `written` on the disk after the disk is fabricated. Aswith the optical storage disk of FIG. 1, the writable optical diskincludes a polycarbonate substrate of support layer 22. The storagelayer 5 of the disk consists of a recording layer 21, which can be a dyepolymer layer, and reflector layer 25, which can be fabricated fromgold. Next to the reflector layer 25 is a lacquer overcoat layer 23,which is applied and then cured. Finally, the markings 24 on the surfaceof the disk provide human and machine readable information.

Referring to FIG. 3A, the process for providing indelible information ona disk is shown. In step 1, the several layers of the optical disk isassembled. In step 32, the storage layer and the reflecting layer of theoptical disk has information applied thereto, typically by using laserradiation to disrupt an interior surface region. In step 33, the lacquerovercoat layer is cured, providing the final step in the fabrication ofan optical disk according to the present invention. In FIG. 3B, analternative process for providing indelible information on an opticaldisk is shown. In step 35, several layers of the optical disk areassembled. However, the surface region of the storage layer andreflective layer, on which the writing is to be inscribed, does not havethe lacquer or protective coating applied thereon. In step 36, themarking of the surface is accomplished. In the preferred embodiment,this marking is accomplished by focused high intensity radiation, suchas focused laser 20 radiation. In step 37, the newly applied protectiveovercoat is applied to the region which has been marked and, ifrequired, the protective coating is cured.

Referring to FIG. 4A, a phenomenological representation of anidentifying mark on an optical disk, capable of having informationwritten thereon after fabrication, is shown. The disk 20 is fabricatedwith a polycarbonate layer 22, a reflecting layer 25, and a lacquerovercoat layer 23. The disruption 4 caused by the laser radiation is inthe reflector layer 25, depending on the intensity of the radiation canextend to or into the polycarbonate layer. In FIG. 4B, the disk 20 isassembled with the polycarbonate layer 22, the reflecting layer 25, andthe lacquer or protective overcoat layer 23. However, a region 25' isnot covered by the lacquer overcoat. The radiation causes a disruptionin a selected region of the reflecting layer 5. The radiation parameterscan be adjusted to provide relatively little impact on the polycarbonatesubstrate. The region without the lacquer overcoat can also haveprinting applied thereto. The additional lacquer overcoat is applied,protecting the disrupted and/or printed region and protecting theinformation represented thereby from compromise.

Referring to FIG. 5, a top view of a optical storage disk, particularlya type of disk 50 known as a compact disk (CD) is shown. The opticaldisk 50 typically has four regions which, with increasing radius can bedefined as the following. Aperture 56 provides a structure to engage aspindle for controlled rotation of the disk. The next area is a clamparea 53. The clamp area 53 typically does not have a storage layerassociated therewith and is used to provide a space wherein the spindlecan be mechanically coupled to the disk without interfering with accessto the data stored on the disk. The mirror area 52 has a storage layerassociated therewith but does not have data embedded therein and,therefore, has a mirror-like appearance. Data area 51 of disk 50 hasdata stored on the storage layer including the reflecting layerassociated therewith and, consequently, because of the structure in thereflecting layer, has a dull appearance when compared to the mirror-likeappearance of mirror area 52. The mirror area 52 can be labelled ineither a machine readable code 55 and/or with human readable markings bythe process described in FIG. 3A and FIG. 3B, and illustrated by FIG. 4Aand FIG. 4B. The disk 50 can therefore be labelled or marked bycarbonizing the plastic in clamp area 53, marking the mirror area 52 ofan optical disk 50 in the presence of an uncured lacquer overcoat layer23 and then curing the lacquer overcoat layer as described above,marking the mirror area 52 of the disk prior to application of theprotective overcoat 41 and curing of the lacquer overcoat region 41after application of the protective coating, or marking the mirrorregion 52 after the protective layer 23 is cured. In the preferredembodiment, a group of alpha/numeric characters 58 are printed in theclamp area and identifying fabrication information. Alpha/numericcharacters are provided in a human readable format and are printed onthe surface of the mirror region 52. Code characters 59 are provided inthe mirror region 52 in a machine readable (i.e., bar code) format.

Referring to FIG. 6, an expanded view of the technique for writinginformation capable of being interpreted by an optical bar code readerin a manner in which the distance of the reader from the center of thedisk is not important, even though the linear velocity of the opticalcode past the reader is a function of radius. The optical bar codemarkings 61 are formed by marking the area between two radius lines 61and 62 from a first radial distance (R₁) 64 to a second radial distance(R₂) 65. With this bar code configuration, for a constant angularvelocity of the disk, the distance of a bar code reader from the centerof the disk is irrelevant. The time each bar interacts optically withthe detector of the optical bar code reader retrieving information fromthe storage is independent of the distance from the disk center.

Referring now to FIG. 7, a block diagram of the apparatus forimplementing the security mechanisms of the present invention is shown.The optical read/write head unit 75 interacts with an informationstorage medium 70 which, in the preferred embodiment, is a writableoptical information storage disk, to retrieve information from and tostore information on, the storage disk (medium) 70. The optical storagedisk 70 includes a recording layer 72 extending over an outer portion ofthe disk. The inner portion of the disk 70 includes embedded characters(identification markings) 71. In the preferred embodiment, theseembedded characters are in a machine-readable format such as an opticalbar code format. The recording layer 72 can extend over a part or all ofthe inner portion of the storage disk 70, but no information istypically stored thereon. When the recording layer 72 does not extendover the inner disk portion, then the inner disk portion is typicallytransparent. Otherwise, when the recording layer 72 extends onto theinner portion of the disk 70, the inner portion of the disk will then beopaque to the light incident thereon. The interaction system includes anoptical read/write head unit 75 for interacting with the recording layerof the optical disk and an optical character recognition unit 76 forinteracting with the embedded characters 71. The embedded characters 71are typically positioned on the inner portion of the optical disk 70.The optical read/write head unit 75 and the optical characterrecognition unit 76 are coupled to a processing and storage unit 77. Theprocessing and storage unit 77 is coupled to an input/output unit 78.The input/output unit 78 includes apparatus and/or components whichpermit an operator to control the interaction with optical disk 70 andto provide for the entry of data into and for the transfer of data fromthe processing and storage unit 77. Input components can include aterminal 78A for entering data and control signals into the system andfor displaying data and operational parameters. Input components canalso include a communication unit 78B which can exchange control and/ordata signal groups between the processing and control unit 77 and aremote location. The processing and storage unit 77 includes componentsresponsive to signals from the optical character recognition unit 76 andsignals from the optical read/write head unit 75 for reformatting datasignal groups into a format which can be processed by and can be storedin processing and storage unit 77. The processing and storage unit 77also provides control signals to the optical character recognition unit76 and to the optical read/write head unit 75 for the opticalillumination and optical sensor components which result in theidentification and transfer of selected data signal groups on thestorage medium 70. In addition, the processing and storage unit 77provides an interface between the input/output unit 78 and associatedsubunits and the optical character recognition unit 76 and the opticalread/write head unit 75. For example, based on the signals from theoptical read/write head unit 73, the processing and storage unit 77 canapply control signals to motor which is part of the optical read/writehead 75. The control signals are used to position the optical componentsof the read/write head unit 75 relative to the storage medium 70, i.e.,thereby providing tracking and focussing control. The processing andstorage unit 77 can also provide control signals to a motor or motors(not shown) associated with apparatus (also not shown) which control themotion of the disk, these control signals determining the engagement androtation of the spindle to the optical storage disk medium 70. Once theappropriate relative movement is established between the optical storagedisk 70 and the components interacting therewith, then the interactingcomponents, i.e., the read/write head unit 75 and the optical characterrecognition system 76 can be electrically activated to transferinformation to and from the optical disk 70. Similarly, an operator canmanipulate the signal input components to specify that the interactionshould take place between the optical read/write head unit 75 and apreselected portion (i.e., identified files) of the storage medium 70.The processing and storage unit 77 receives the signals entered into theinput/output unit 78 and provides the proper control signals to positionthe read/write head unit 75 in an appropriate position relative to theoptical disk 70, activates radiation source and sensor components of theread/write head unit 73, and controls the transfer of the identifieddata files between the read/write head unit 75 and optical disk 70. Inaddition, the processing and storage unit 77 can include an interactionsystem identification signal group 77A. The use of the interactionsystem identification signal group 77A is discussed below in conjunctionwith identification signal groups associated with the optical storagedisk. However, the interaction system identification number determinesthe appropriateness of the desired interaction with the storage disk 70.

Referring next to FIG. 8, a representation of the organization of thefiles 800 stored on the optical storage medium in the recording layer72, according to the present invention, is shown. A control file 801 anda plurality of data files 802-804 are stored on the medium. The controlfile 801 can include a storage medium identification signal group 801A,a code/format file 801B, and a directory file 801C. The storage mediumidentification signal group 801A is a character group which is relatedto the character group (identification markings) 71 embedded in theoptical storage disk medium. During initialization of the interactionsystem in preparation for the interaction with the optical storagemedium, the embedded optical characters and the control file 801 areread from the storage medium 70 and entered in the processing andstorage unit 77. The embedded characters (identification markings) arecompared, by the processing and storage system 77, with the mediumidentification signal group 801A stored in the control file 801. Whenthese character groups are determined to be consistent, then theinformation on the storage medium will be deemed to be uncompromised andfurther interaction between the storage medium interaction system andthe storage medium 70 can continue. When the identification charactersand the identification signals are determined by the processing andstorage unit 77 not to be consistent, then the interaction between thestorage medium 70 and interaction system will be halted. Thisconsistency between quantities entered at different times on the storagemedium provides an indication that the data on the storage medium hasnot been compromised. The code/format file 801B provides information tothe storage medium interaction system, especially the processing andstorage unit 77, as to how the information on the storage medium 70 isformatted and/or encoded. The processing and storage unit 77 isresponsive to these data characterizations and translates the datasignal groups on the storage medium 70 into data signal groups which canbe processed by the processing and storage unit 77. Unless reformattedand decoded, the data signal groups can not be processed by theprocessing and storage unit 77 and will not be useful to the (operatorof the) interaction system. The directory file 801C is a file, typicallyprovided in with the storage of signal groups which relates anidentification of a particular data file 802-803 with a specificlocation on the storage medium, the identification permitting theprocessing and storage unit to generate control signals which result inthe retrieval of a specified data file. In the case of pre-recordedmedium, the directory files will be fixed in the storage medium. In thecase of writable media, the directories will have the addressinformation written therein when the data files are stored on thestorage medium. Similarly, when information is being written on thestorage medium, identifying signal groups associated with the data filesare compared with the embedded identification marking on the medium orwith the medium identification signal group. This comparison can be usedto determine if the data signal group(s) being stored is appropriate tothe particular storage disk.

Referring next to FIG. 9, a flow chart of the interaction between theoptical storage disk 70 and the interaction system illustrated in FIG. 7is shown. In step 901, the process is initiated by having theinteraction system engage the optical storage disk 70. In the preferredembodiment, the optical storage disk 70 is physically engaged by theinteraction system by means of a rotatable spindle. In step 902, theactivation of the interaction typically results from operatorintervention through a keyboard associated with terminal 78A of theinput/output unit 78. Upon activation of the interaction system 75, Thespindle and the optical disk will begin rotation. The optical characterreader unit 76 identifies the embedded optical characters on the diskand transfers these characters to the processing and storage unit 76 instep 903. Generally simultaneously, the optical read/write head unit 73retrieves the control file 801 from the optical storage disk 70 in step904. In step 905, the embedded optical character group 71 is thencompared with the medium identifying signal group 801A included in thecontrol file 801 in step 905. When the optical character group 71 is notconsistent with medium identifying signal group 801A, the interactionbetween the interaction system 75 and the optical disk 70 will beterminated in step 906. Otherwise the interaction with the optical disk70 will continue. Step 907 provides for the situation wherein, inaddition to the character group 71 and the medium identifying signalgroup 801A which are both stored on the optical disk 70, the interactionsystem itself can be provided with a system identification code 77A, thesystem identification code typically being stored in the processing andstorage unit 77. In step 907, the interaction system compares thisinteraction system identification number 77A with signal groups (i.e.,the optical character group 71 and the medium identification signalgroup 801A) from the optical disk 70 to determine if an interactiontherebetween is permitted. If the interaction system does have aninteraction system identification number 77A and this code is notconsistent with interaction between the interaction system and thecoupled optical storage disk 70, the interaction between the interactionsystem 75 and the optical storage disk 70 is terminated in step 908.When further interaction between the interaction system and the opticalstorage disk 70 is permitted, then, in step 909, data signal groups inthe control file 801, i.e, the code/format file 801B, are used by theprocessing and storage unit 77 to permit a translation of retrieved datafile(s) to a text/format capable of being manipulated by the processingand storage unit 77. Similarly, the decode/format file 801B of thecontrol file 801 can be used to prepare a data file for storage on theoptical disk in a format and, if applicable, encoded in a mannerconsistent with the data files already stored on the disk. If compromiseof the security of the information stored on the optical disk is aconcern, then the logic signals stored on the optical disk can beencoded in a manner determined by the decode/format file 801B. Steps 910through 912 represent the process of the retrieval of information fromthe optical storage disk 70 after the initialization of the interactionsystem. Steps 914 and 915 represent the process of storing file on thestorage medium. An interaction between the interaction system and thestorage medium can include only a data file retrieval or a data filestorage. In step 910, the file directory 801C of the data files storedon the optical storage disk 70 is made available to the operator.Typically, the directory file 801C is part of the control file 801 whichis transferred to the processing and storage unit 77. Directory file801C can be transferred to the processing storage unit 77 as part of thecontrol file 801 or can be transferred separately. Then, upon input fromthe operator, the directory 801C is displayed, by way of specificexample, on monitor of terminal 78A. The operator can then select one ofthe files (802 through 803) for transfer to the interaction system instep 911. The decode/format procedures specified by the control file areused to translate the transferred file into a text and format needed formanipulation in the interaction system in step 912. In step 913, theprocedure for which the data file was retrieved is executed. Forexample, if the data file is received for display, the processed text isdisplayed on the monitor of terminal 78A. After the text has beenprocessed in the manner for which it was retrieved, or if the text isnew, e.g., entered from the communication unit 78B or other data entrydevice coupled to the input/output unit 78, then, the resulting file canbe stored on the optical storage disk 70. In step 914, a file to bestored on the storage medium is identified. In step 915, the file to bestored on the coupled optical storage disk is encoded and/or formattedin a manner indicated by the control file. In step 916, a fileidentification signal group is compared with the control file mediumidentification signal group and/or with the embedded characters. Thefile identification signal group can be the interaction systemidentification number, or the file identification number can be morespecific to the contents of the data file to be stored on the coupledstorage disk. When the two quantities being compared are not consistent,then the storage of the data file on the storage disk is terminated instep 917. If, however, the two signal groups are consistent, then thefile is stored on the optical storage disk in step 918. In step 920, adetermination is made as to whether a new procedure involving thecoupled optical disk is desired. When no new interaction is desired, theinteraction between the interaction system and the storage disk mediumis terminated in step 921. Otherwise, the process is reentered at anappropriate step in the procedure, i.e., step 910 is shown in FIG. 9B.

2. Operation of the Preferred Embodiment

Briefly summarized, according to one aspect of the present invention,the marking of the disk, important in providing data file security forthe disk, is performed on the storage layer of an optical storage disk,however, the marking is performed prior to the curing of the lacquerovercoat layer according to one embodiment and prior to the applicationof the lacquer coating in a second embodiment. In the optical storagedisk of the present invention, the overcoat is fabricated from a lacquermaterial for which ultraviolet light provides the curing reaction andreduces the elasticity of the overcoat. This marking takes the form ofan optical character group. The optical character group is used by asystem interacting with the optical storage disk (or other opticalstorage medium) to permit a record of the activity involving the diskand to provide security with respect to the contents of the disk.

The purpose of the invention is to provide improved data file securityfor the files on optical storage medium which can provide a high densitydata storage. This data file security is particularly important for thewritable optical storage medium and the rewritable optical storagemedium, wherein data files can be stored on the medium at various times.The greater requirement for security is the result of the lack ofcontrol over the stations which can add the new data files to the disk.The technique for providing the additional security is to provide thestorage medium with indelible identification markings, i.e., theembedded optical characters, which permanently identify the storagemedium in which the markings are embedded. The material stored on thestorage medium is then provided with a control file having mediumidentification signal group related to the embedded optical characters.The system interacting with the optical storage medium, programmedeither through hardware or through software, requires consistencybetween these character/signal groups before further interaction cantake place.

The technique for the application of an indelible identification marksto an optical disk can be briefly summarized as follows. According toone aspect of the present invention, the marking of the disk isperformed on the storage layer, however, the marking is performed priorto the curing of, or prior to the application of the lacquer orprotective overcoat layer. Where not previously applied, the protectiveovercoat is then applied. The lacquer material is then exposed toultraviolet light which provides the curing for the lacquer overcoatlayer. By marking storage layer prior to curing of the lacquer overcoatlayer, the lacquer overcoat layer, when present remains pliable enoughto absorb damage that would otherwise result from the disruption of thepolycarbonate layer.

In the optical disk capable of having information written or storedthereon after fabrication of the storage medium, the present inventioncan be implemented in the following manner. An interaction system would,in the prior art, not have the apparatus to interpret the embeddedcharacters. Without the ability to read and interpret the embeddedcharacters automatically, information can be retrieved from the opticalstorage medium or stored on the optical storage medium which is notappropriate. Therefore, the interaction system is provided with anoptical character recognition unit can be used to identify the identifythe embedded characters and transfer the characters to the processingand storage unit. In addition, a medium identification signal groupwhich is part of the stored data on the storage medium is transferred tothe processing and storage medium. The processing and storage unit canautomatically insure the consistency of the data retrieved from thestorage medium or written on the storage medium by comparing theembedded characters and the medium identification signal group. In otherwords, the simultaneous presence of the (visible) optical characterinformation and a consistent data signal group stored in a predeterminedlocation (typically referred to as a header) on the storage mediuminsures that the data files stored on the disk has not been compromised.In addition, data files to be stored on the storage medium must beconsistent with these storage medium indicia. Therefore, the data filesto be stored may have a file identification signal group. For example,the data files to be stored may be photographic images. The fileidentification signal group associated with the photographic images canbe related to the owner of the images. The owner of the photographicimages will have a consistent medium identification signal group on thestorage medium to insure that the photographic images are stored on thecorrect storage media. A system identification signal group associatedwith the interaction system can be used to control interaction with thesystem with the storage medium through comparison with one of theembedded characters or with the medium identification signal group. Inthe absence of a consistent comparison, the interaction system will beprevented from interaction with the storage medium. As will be clear tothose familiar with security systems, the use of processing apparatus tocompare automatically the indicia on the storage medium and in theinteraction system provides protection against unauthorized interactionwith the storage medium.

The present invention can be provided with a further security feature.The data files stored on the storage medium can be encoded. Thus, inorder to process these files, a decoding of the data files must beperformed. The `key` to the decoding can be contained in the code/formatfile of the control file. In this implementation, any data file to bestored on the optical medium must first be encoded using the `key` inthe storage medium control file. It will be clear that interactionsystem must be able to interpret the code. This decoding `key`interpretation capability can be included in the interaction system as ahardware or a software process.

While the storage medium has been described both in general terms and interms of an optical disk, other medium for the storage of opticalinformation, which have the general layer structure in which opticalcharacters can be embedded therein, can use the present inventionadvantageously. For example, the optical tape storage medium canadvantageously use the present invention. In addition, the storage layerhas been described as generally including a reflective layer. The use ofthe reflection of radiation from a storage disk is generally used toidentify the information stored thereon. However, the use of an opticalstorage disk which relies on the interaction of transmitted radiationwith the storage media can use the present invention.

The present invention finds an important application in the field of thewritable CD disk. One current application is to allow the owner of thewritable CD disk to add files when convenient. The present inventionprovides a measure of security for ascertaining that the files on theoptical storage medium have not been compromised and for restricting theaccess to the stored material. In addition, only certain preselectedgroups of files can be added to the disk.

In the preferred embodiment, the optical characters are placed in theoptical bar code format. The preferred embodiment also includes aseparate bar code reader in the system interacting with the opticalstorage medium. It will be clear that the embedded characters can haveformat different from the optical bar code format. It will be also beclear that the read/write head can be used to identify the embeddedcharacters without departing from the invention.

Similarly, while the invention has been described with particularreference to a preferred embodiment, it will be understood by thoseskilled in the art that various changes may be made and equivalents maybe substituted for elements of the preferred embodiment withoutdeparting from invention. In addition, many modifications may be made toadapt a particular situation and material to a teaching of the inventionwithout departing from the essential teachings of the present invention.By way of specific example, the lacquer layer used proximate the storagelayer could be implemented with any material having properties suitablefor the protection of the storage layer. By way of a different example,in the erasable optical disk, the storage layer can be selected of amaterial wherein an impinging radiation beam this appropriate parameterscan provide a non-reversible change can take place. The non-reversiblechange protected from compromise by the protective overcoat layer.

As is evident from the foregoing description, certain aspects of theinvention are not limited to the particular details of the examplesillustrated, and it is therefore contemplated that other modificationsand applications will occur to those skilled in the art. It isaccordingly intended that the claims shall cover all such modificationsand applications as do not depart from the true spirit and scope of theinvention.

What is claimed is:
 1. A method of protecting files stored on an opticalwritable disk, said method comprising the steps of:physically embeddinga first identification signal group in a writable optical disk; storinga second identification signal group in a file written on said writableoptical disk; on initiation of interaction between an interaction systemand said writable optical disk, transferring a representation of saidfirst and said second identification signal group to a signal processingunit of said interaction system; comparing said first and said secondidentification signal group representation in said signal processingunit and continuing interaction between said interaction system and saidwritable optical disk only when said comparison between said first andsaid second identification signal group representations is positive; anddecoding a transferred file prior to processing by said processing unit;wherein said interaction system has a third identification signal groupassociated therewith, said method further comprising the steps oftransferring a representation of said third identification signal groupto the signal processing unit of said interaction system and comparingsaid third and first identification signal group representations in saidsignal processing unit and continuing interaction between saidinteraction system and said writable optical disk only when saidcomparison between said first and third identification signal grouprepresentations is positive.
 2. The method of claim 1 further comprisinga step of encoding a current file prior to a writing of said currentfile on said writable optical disk.
 3. A method of protecting filesstored on an optical disk, said method comprising the steps of:reading abar code character group embedded in said optical disk and reading amedium identification signal group stored on said optical disk with areading unit of an interaction system; transferring said bar codecharacter group and said medium identification signal group from saidreading unit to a signal processing unit of said interaction system;comparing said bar code character group and said medium identificationsignal group with said signal processing unit of said interactionsystem; continuing interaction between said interaction system and saidoptical disk when said comparison between said bar code character groupand said medium identification signal group is indicative of anon-compromised disk; reading a file identification signal group from afile stored on said disk with said reading unit of said interactionsystem; transferring said file identification signal group to saidsignal processing unit of said interaction system; comparing said fileidentification signal group with said medium identification signal groupwith said signal processing unit of said interaction system; andcontinuing interaction between said interaction system and said opticaldisk when said comparison between said file identification signal groupand said medium identification signal group is indicative of anon-compromised disk.
 4. A method of protecting files stored on anoptical disk as claimed in claim 3, further comprising the stepsof:comparing a system identification signal group stored in saidinteraction system with at least one of said bar code character groupand said medium identification signal group; and continuing interactionbetween said interaction system and said optical disk when saidcomparison between said system identification signal group and at leastone of said bar code character group and said medium identificationsignal group is indicative of a non-compromised disk.